Zitadel MCP

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already indicate this is a non-readOnly, non-destructive, non-idempotent operation. The description adds useful behavioral context about authentication method (JWT keys) that isn't captured in annotations, but doesn't disclose other important traits like rate limits, error conditions, or what happens on duplicate userName. No contradiction with annotations exists.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two concise sentences that are front-loaded with the core purpose. Every word earns its place - first sentence states what the tool does, second adds crucial authentication context. No wasted words or redundant information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a creation tool with good annotations (readOnlyHint=false, destructiveHint=false) and comprehensive schema coverage, the description provides adequate context about the tool's purpose and authentication method. However, without an output schema, it doesn't describe what gets returned (e.g., user ID, credentials), leaving a minor gap in completeness.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

With 100% schema description coverage, the schema already documents all 4 parameters thoroughly. The description doesn't add any parameter-specific semantics beyond what's in the schema (e.g., doesn't explain userName uniqueness constraints or accessTokenType implications). Baseline 3 is appropriate when schema does the heavy lifting.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the specific action ('Create a new service account') and resource ('machine user for API access'), distinguishing it from sibling tools like 'zitadel_create_user' (regular user) and 'zitadel_create_service_user_key' (key for existing service account). It adds valuable context about authentication method (JWT keys vs passwords).

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage context ('for API access', 'authenticate via JWT keys') but doesn't explicitly state when to use this tool versus alternatives like 'zitadel_create_user' or 'zitadel_create_oidc_app'. No guidance on prerequisites, permissions needed, or when-not-to-use scenarios is provided.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.